1. Field of the Invention
This invention relates generally to point-to-point protocol (PPP) communications using automatic protection switching (APS).
2. Description of Related Art
In networking, the PPP is a data link protocol used to establish a direct connection between two nodes over serial cable, phone line, trunk line, cellular telephone, specialized radio links, or fiber optic links. Most Internet service providers use PPP for customers' dial-up access to the Internet. Two common encapsulated forms of PPP, Point-to-Point Protocol over Ethernet (PPPoE) or Point-to-Point Protocol over ATM (PPPoA), are used in a similar role with Digital Subscriber Line (DSL) Internet service.
Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer protocol which encodes data traffic into small fixed-sized cells. ATM provides data link layer services that run over Layer 1 links. ATM differs from other technologies based on packet-switched networks such as the Internet Protocol or Ethernet which use variable sized packets known as frames when referencing layer 2. ATM is a connection-oriented technology, in which a logical connection is established between the two endpoints before the actual data exchange begins.
PPP is often used to act as a data link layer protocol for connection over synchronous and asynchronous circuits. For such uses, PPP has largely superseded the older, non-standard Serial Line Internet Protocol (SLIP), and standards mandated by telephone companies such as Link Access Protocol, Balanced (LAPB) in the X.25 protocol suite. PPP was designed to work with numerous network layer protocols, including Internet Protocol (IP).
One approach to failure detection in routers used for PPP communications is APS. In distributed routing systems with APS protection on routers, multilink PPP (MLPPP or ML-PPP) is an extension to the PPP. MLPPP is a bandwidth-on-demand protocol that can connect multiple links between two systems as needed to provide bandwidth on demand. The technique is often called bonding or link aggregation.
For example, the two 64-Kbit/sec B channels of ISDN can be combined to form a single 128-Kbit/sec data channel. Another example would be to bind one or more dial-up asynchronous channels with a leased synchronous line to provide more bandwidth at peak hours of the day.
Many PPP and ML-PPP communications systems using APS routers experience a temporary data loss during an APS switch. This data loss is undesirable. Thus, there is a need for a mechanism and method that minimizes data loss in PPP/ML-PPP communications systems using APS routers during an APS switch.
The foregoing objects and advantages of the invention are illustrative of those that can be achieved by the various exemplary embodiments and are not intended to be exhaustive or limiting of the possible advantages which can be realized. Thus, these and other objects and advantages of the various exemplary embodiments will be apparent from the description herein or can be learned from practicing the various exemplary embodiments, both as embodied herein or as modified in view of any variation which may be apparent to those skilled in the art. Accordingly, the present invention resides in the novel methods, arrangements, combinations and improvements herein shown and described in various exemplary embodiments.